<template>
  <div class="spec-preview">
    <img :src="skuImageList[dataIndex]?.imgUrl" />
    <div class="event" @mousemove="mousemove"></div>
    <div class="big">
      <img :src="skuImageList[dataIndex]?.imgUrl"  ref="bigImgEle"/>
    </div>
    <div class="mask" ref="maskEle"></div>
  </div>
</template>

<script>
  export default {
    name: "Zoom",
    data(){
      return {
        dataIndex:0
      }
    },
    props:['skuImageList'],
    mounted() {
      this.$bus.$on('getZoomIndex',(index) => {
          this.dataIndex = index
      })
    },  
    methods: {
      //放大镜
      mousemove(e){
        //鼠标到外层边缘的距离
        const maskToOut = {
          left: e.offsetX,
          top: e.offsetY
        }
        //计算蒙版位置
        const maskLoaction = {
          x: maskToOut.left - this.$refs.maskEle.offsetWidth / 2,
          y: maskToOut.top - this.$refs.maskEle.offsetHeight / 2
        }
        //临界值
        if(maskLoaction.x < 0){
          maskLoaction.x = 0
        }else if(maskLoaction.x >= e.target.clientWidth - this.$refs.maskEle.offsetWidth){
          maskLoaction.x = e.target.clientWidth - this.$refs.maskEle.offsetWidth
        }

        if(maskLoaction.y < 0){
          maskLoaction.y = 0
        }else if(maskLoaction.y >= e.target.clientHeight - this.$refs.maskEle.offsetHeight){
          maskLoaction.y = e.target.clientHeight - this.$refs.maskEle.offsetHeight
        }

        //赋值
        this.$refs.maskEle.style.left = maskLoaction.x + 'px'
        this.$refs.maskEle.style.top = maskLoaction.y + 'px'
        //大图位移
        this.$refs.bigImgEle.style.left = -2*maskLoaction.x + 'px'
        this.$refs.bigImgEle.style.top = -2*maskLoaction.y + 'px'
      }
    },
  }
</script>

<style lang="less">
  .spec-preview {
    position: relative;
    width: 400px;
    height: 400px;
    border: 1px solid #ccc;

    img {
      width: 100%;
      height: 100%;
    }

    .event {
      width: 100%;
      height: 100%;
      position: absolute;
      top: 0;
      left: 0;
      z-index: 998;
    }

    .mask {
      width: 50%;
      height: 50%;
      background-color: rgba(0, 255, 0, 0.3);
      position: absolute;
      left: 0;
      top: 0;
      display: none;
    }

    .big {
      width: 100%;
      height: 100%;
      position: absolute;
      top: -1px;
      left: 100%;
      border: 1px solid #aaa;
      overflow: hidden;
      z-index: 998;
      display: none;
      background: white;

      img {
        width: 200%;
        max-width: 200%;
        height: 200%;
        position: absolute;
        left: 0;
        top: 0;
      }
    }

    .event:hover~.mask,
    .event:hover~.big {
      display: block;
    }
  }
</style>